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At About 20 Meteors Per Hour, Orionid Shower Will Be Among October's Celestial Highlights

For October, the two largest planets serve as the night sky's bookends: Jupiter shores up the evening; Saturn , the morning.

Starting after sunset, find giant Jupiter in the southwest above the horizon. This planet is visible at negative first magnitude (very bright) and is in the constellation Libra; as October continues, it appears to move closer to the sun.

Mercury makes a cameo in mid-October, joining Jupiter in the dusk sky. Getting ready for November's transit across the sun, Mercury is seen at zero magnitude (bright).

Sharp observers may find the sliver of a new moon sashaying past Mercury and Jupiter at dusk Oct. 24. By the end of the month, Jupiter and Mercury will have retreated to the horizon.

If you're a morning person, look to the east-northeast to find regal Saturn rising with the constellation Leo in the mid-morning hours. By dawn, this zero magnitude (bright) planet will be high in the east. As October continues, this gaseous giant rises earlier, giving gazers more time to telescopically enjoy the rings.

The Orionid meteor shower will peak the morning of Oct. 21, with about 20 meteors per hour, according to the American Meteor Society ( http://www.amsmeteors.org ).

Meteor showers occur when Earth intersects the dusty trail of long-gone comets, which in this case is our old friend Halley's Comet. These tiny pieces of comet dirt strike our upper atmosphere, burn and create a glorious trail.

We turn our clocks back at 2 a.m. Oct. 29. This will be the last time, in the foreseeable future, that we will turn our clocks back in October. Thanks to the Energy Policy Act of 2005, next year clocks will move forward March 11 (the second Sunday of March) and back Nov. 4 (the first Sunday of November). The U.S. Naval Observatory posts a brief history online: http://aa.usno.navy.mil/faq/docs/daylight_time.html .

Down-to-Earth Events

Oct. 5 -- Astronomer Daniel Jontof-Hutter on the "Age of Discovery for Planets" at the University of Maryland Observatory open house, College Park. 9 p.m. Information: http://www.astro.umd.edu/openhouse/index.html .

Oct. 20 -- Astronomer Megan Decesar explains "Neutron Stars and Pulsars" at the University of Maryland Observatory open house, College Park. See the heavens through a telescope afterward. 9 p.m. Information: http://www.astro.umd.edu/openhouse/index.html .

Oct. 21 -- "Exploring the Sky," hosted by the National Park Service and the National Capital Astronomers at Rock Creek Park, 7:30 p.m. Information: http://www.capitalastronomers.org or http://www.nps.gov/rocr .